new loader

All Megasquirt 1 support questions. See also the Documentation

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fiat132
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new loader

Post by fiat132 »

hey there everone
i have a few questions. i am running ms1 v2.2 and i just upgraded to extra code, 29q2 and at the same time i made a new ms to relay cable connector.i went to a computer store and i bopught a 25 wire cabe and i soldered it to tthe connector.they are still packed together as one cable though...i just soldered the ends.i hooked up the correct wires and the shield too and i started the car. the problem i am running into is that the dial in the megatune shows twice the rpm i am running, i guess...its more.the ve table is almost correct though...my guess....my table is up to 6000 rpm but megatune shows the dial upto 8000.is it normal with this version, 613 i think. there seems to be a problem with the car...the idle is very unsteady...like its missing or something..i dont know...and at the same time the fan output block on megatune sometimes goes green..i think with the engine miss....is it the cable carrying to much noise or something
please help
milosch01
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Post by milosch01 »

Any idea what guage wires you have on that cable. The only ready to buy 25 pair cable I know of would be for telephone, and those would be way too small.
fiat132
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Post by fiat132 »

i dont know..i remember it says 300 volts on it
milosch01
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Post by milosch01 »

Do they look like the cables already under the hood, or more like vermicelli ;) Seriously, they do need to be of a certain guage as documented.
fiat132
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Post by fiat132 »

what vermicelli?????
sounds funny
milosch01
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Post by milosch01 »

The very small type of stringy pasta. Anyway, take a look at http://en.wikipedia.org/wiki/American_wire_gauge OR http://www.powerstream.com/Wire_Size.htm to get an idea.
MegaScott
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Post by MegaScott »

Have you input your engine parameters into the constants page? sounds like you have a four cylinder engine, with 6cylinders in the constants?

I don't condone the use of the cable you mention, but I have seen it used with success in applications that use high impedence injectors, you should double up on 12Vpower, Injector drive, and as many ground wires as you can spare.

Image
fiat132
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Post by fiat132 »

i dont think so..i will double check...it seems to be running fine...except for the stuff i mentioned
fiat132
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Post by fiat132 »

i checked and everything is fine..its reading double the rpm...could it be a problem with thye wiring.the output 4 slot keeps coming on and off randomly :? :?
fiat132
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Post by fiat132 »

i tried today and everything is fine on the constants page. its a 4 cylinder and if i switch it to eight, it readfs the right rpm!!!!
any ideas?????
MegaScott
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Post by MegaScott »

What is the method you are using to trigger the Tach input of the Megasquirt?
fiat132
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Post by fiat132 »

i have a shield on wire 24 and the shield is connected to pin 25. evrything was fine until i upgraded the code and changed the cable.i am triggering from the negative side of the coil
fiat132
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Post by fiat132 »

by the way..i changed the cable and i am now running 1mm wires all the way through
MegaScott
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Post by MegaScott »

fiat132 wrote:i have a shield on wire 24 and the shield is connected to pin 25. evrything was fine until i upgraded the code and changed the cable.i am triggering from the negative side of the coil
Did you install the diodes D5 and D8 in your board?

Maybe someone better knowlegable about negative coil triggering can chime in with some suggestions.
fiat132
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Post by fiat132 »

on the extra page...it says to remove those while upgrading to the gm hei....could it be that i am not running the module now....would this problem be solved when i hook up the ignition???
MegaScott
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Post by MegaScott »

fiat132 wrote:on the extra page...it says to remove those while upgrading to the gm hei....could it be that i am not running the module now....would this problem be solved when i hook up the ignition???
In response to my other question, does what you say here mean that you have not installed any of the diodes?

You need at least D5 installed when connecting to the negative of the coil, you may also need Ed cap installed as well.

As quoted from the assembly manual -
47. Install and solder R10 (390H-ND, 390 ohm, ½ watt, orange-white-brown). This resistor should be mounted roughly 1/8" (2mm) above the surface of the PCB.

Also, the value of this resistor may have to be changed depending on application - start with the supplied value, and if gets hot while the engine is running, then increase the value, in steps, up to 10K (like 470 ohms, 560 ohms, 680 ohms, 1K, ...), or even more in some applications (consult the MegaSquirt Forums list for advice). However, do not adjust this resistor on assembly, unless you have a good reason to do so.

48. Install and solder D5 {1N4001DICT-ND}. This is the famous Wing Diode - you will want this (reduces tach signal false-triggering).

49. For most installations, diode D8{1N4733AMSCT-ND}, the John Zener, 5.1V, marked 1N4733) is not needed. If you do not install D8, you must install a jumper (made from a snipped off lead) in its place.

Note: this diode D8 is needed only if the ignition system has a large offset bias - most systems do not have such a bias. So, to start, you can either solder in a jumper wire in this location, or, you can install the diode D8, and then install a jumper around the two leads of the diode - in effect shorting it out. The latter will allow you to snip the jumper later on if needed, putting the diode back in circuit. Solder the diode in observing the banded end as on the board, then solder a wire jumper across the diode itself.
51. Install and solder C12, the Ed capacitor (399-1818-1-ND, 0.001µF, 102 marking). The value of this capacitor may need to be increased if there are noise problems with the tach signal - values up to 0.1uf will work. The 0.001uf value is a good starting point.
fiat132
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Post by fiat132 »

i am sorry i forgot to mention thta i bought the unit pre assembled. d5 was there when i wasnt running the extra code. when i did the upgrade, i reemoved it to run the gm hei...but i havent connected it yet and i am still triggering from the negative side of the coil
i did the modifications stated here
http://megasquirt.sourceforge.net/extra/setup-hei7.html
but i havent connected the hei module yet
MegaScott
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Post by MegaScott »

OK.

When you make modifications to your board, you need to run the configuration you modified the board for.

What is happening is you are getting false triggering, 2 or more triggers for each ignition event, that's why your RPM reads double.

If you really need to run with the configuration you have now, you must configure the board in the proper way, the configuration you say you have now is to support an HEI 7 or 8 pin module, you need to run that, or a similar configuration, or don't run at all.
fiat132
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Post by fiat132 »

ok...thanks megascott...
i am glad its not the wiring...
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